Algorithms for Identification of Nearly-Coincident Events in Calorimetric Sensors

For experiments with high arrival rates, reliable identification of nearly-coincident events can be crucial. For calorimetric measurements to directly measure the neutrino mass such as HOLMES, unidentified pulse pile-ups are expected to be a leading source of experimental error. Although Wiener filtering can be used to recognize pile-up, it suffers errors due to pulse-shape variation from detector nonlinearity, readout dependence on sub-sample arrival times, and stability issues from the ill-posed deconvolution problem of recovering Dirac delta-functions from smooth data. Due to these factors, we have developed a processing method that exploits singular value decomposition to (1) separate single-pulse records from piled-up records in training data and (2) construct a model of single-pulse records that accounts for varying pulse shape with amplitude, arrival time, and baseline level, suitable for detecting nearly-coincident events. We show that the resulting processing advances can reduce the required performance specifications of the detectors and readout system or, equivalently, enable larger sensor arrays and better constraints on the neutrino mass.

HOLMES: The electron capture decay of [Formula: see text]Ho to measure the electron neutrino mass with sub-eV sensitivity

The European Research Council has recently funded HOLMES, a new experiment to directly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy released in the decay of [Formula: see text]Ho. The calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in experiments with beta spectrometers. This measurement was proposed in 1982 by A. De Rujula and M. Lusignoli, but only recently the detector technological progress allowed to design a sensitive experiment. HOLMES will deploy a large array of low temperature microcalorimeters with implanted [Formula: see text]Ho nuclei. The resulting mass sensitivity will be as low as 0.4 eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1 eV. We outline here the project with its technical challenges and perspectives.

Out-of-hospital delivery in Washington State, 1975 to 1977

The annual rate of out-of-hospital deliveries in Washington State increased from 1.6% in 1975, to 2.4% in 1977. Birth certificates, linked birth and death certificates files, and log books from tertiary referral hospitals were used to investigate this trend. As parity increased, rates of home delivery (HD) also increased (p less than 0.001). However, alternative birth center delivery (BCD) rates did not change with parity (p greater than 0.1). HD rates and BCD rates increased with birth weight (p less than 0.001). Obstetric professionals attended 91% of BCD as compared to 65% of HD. Fifty-four percent of the women in the BCD group had 10 or more prenatal visits compared to 40% in the HD group. Infant mortality rates were lower with BCD than with HD. However, our analysis of mortality was limited by countervailing biases inherent in the data. We concluded that out-of-hospital deliveries were a heterogeneous group that in future studies should be stratified into groups of birth center deliveries and home deliveries.